Ventilation and hood repair

The hood is the only appliance in the kitchen whose whole job is to pull outside air through itself. Within a couple of miles of the Atlantic, that job is what kills it.

The blower

A blower motor spinning a squirrel-cage wheel is a balanced assembly. Grease aerosol lands on the wheel, salt lands in the grease, and the two of them build a crust. The crust never builds evenly. An out-of-balance wheel puts a side load on bearings specified for none, and from there the failure is a countdown.

The order of symptoms is consistent enough to diagnose over the phone, though we will still come and confirm it:

1. A rumble that is worst at the lowest speed. Imbalance loading a bearing that is starting to dry.
2. A rattle on spin-down. The wheel is out of true.
3. A whine at all speeds, rising over weeks. The bearing is now the fault.
4. Silence. Thermal cutout, or the winding.

Stage one is a cleaning job with a modest bill. Stage four is a motor.

Internal, in-line and external blowers

Where the blower sits changes how long it lasts. An external roof- or wall-mounted blower gets weather but also gets airflow that dries it out between uses. An internal blower sits in a warm cabinet where condensate forms every time the kitchen cools down after cooking. Warm, damp, salty and greasy is the complete set of conditions for corrosion, and internal blowers on this coast show it.

In-line blowers, mounted in the duct run in an attic, split the difference and add a problem of their own: an attic in North Florida is a punishing place for a motor in July, and nobody ever hears the early rumble because it is thirty feet away and above a ceiling.

Ducting, which is half of every airflow complaint

When a hood moves less air than it used to and the motor sounds healthy, the duct is the suspect. Long runs, extra elbows, a crushed flexible section, or a roof cap whose damper has corroded part-open are all common here. A damper that sticks shut is an airflow complaint. A damper that sticks open is a humidity and insect complaint, and it is the one that gets ignored until August.

Baffle filters are the part owners can maintain themselves, and the rule is to wash them on a schedule rather than when they look dirty. By the time a filter looks bad, the grease it should have caught is already downstream in the housing and the duct.

Controls and lighting

Speed controls fail in a pattern: one speed dead, then two. On a unit with electronic control that is usually the board; on a mechanical rotary it is the switch. Halogen and LED lamp faults are usually the transformer or driver, not the lamps, and a driver that lives in a hot cabinet above a cooking surface has the same short life as any other electronic in that position.

Downdrafts

Downdraft units add a lift mechanism to everything above. They stall for mechanical reasons — a drive belt or cable, a track that has taken a spill and gone sticky, or an obstruction the unit cannot sense. A downdraft that rises part way and reverses is usually reporting an obstruction it is right about.

What a visit looks like

Flat diagnostic fee, credited toward the repair. We will tell you honestly whether a blower is a clean or a replacement, because on the coast the answer depends on how far the corrosion has already gone.